Multi-exposure control device for cameras

Abstract

The multi-exposure control device is provided with an automatic mechanism for stopping-down the diaphragm from an open position prior to exposure. A diaphragm adjusting ring stops the stopping-down operation at the pre-selected diaphragm aperture. An automatic exposure time control signal is generated from the light passing through the objective lens and stopped-down diaphragm aperture. A shutter speed selecting member provides a first mode for manual selection of the shutter speed and a second mode for automatic shutter exposure control. The device is switchable between a manual exposure control mode wherein both the shutter speed and diaphragm aperture are manually selected prior to exposure and an automatic exposure control mode having an automatic shutter speed control or automatic diaphragm aperture control. With the shutter speed manually selected, the exposure control device compares an output signal corresonding to the manually selected shutter speed with the automatic exposure time control signal to stop the aforesaid diaphragm stopping-down operation for automatic control of the diaphragm and then the shutter speed is automatically controlled according to the output of the automatic exposure time control signal circuit, which output is dependent upon the adjusted diaphragm aperture. In the automatic shutter speed control mode, the shutter speed is controlled to afford an optimum exposure for the diaphragm aperture which has been previously manually adjusted prior to exposure.

What is claimed is: 
     
       1. A multi-exposure control device for a camera, comprising: an objective lens and a variable diaphragm;   means for automatically stopping-down said diaphragm from an open position prior to commencement of exposure in association with the release operation of the camera shutter mechanism;   diaphragm adjusting means for stopping said diaphragm;   means for selecting shutter speed providing a first mode for manual selection of shutter speed and a second mode for automatic shutter speed control;   means for generating an output signal corresponding to the shutter speed manually selected in said first mode;   means for producing an automatic exposure time control signal corresponding to the light passing through said objective lens and said diaphragm aperture;   a diaphragm control circuit for comparing said automatic exposure time control signal with said output signal and enabling said diaphragm adjusting means to stop the diaphragm when a predetermined relationship exists between said output signal and said automatic exposure time control signal;   means for stopping said diaphragm at a manually selected aperture;   means for terminating exposure;   an exposure time control circuit for controlling said means to terminate exposure in accordance with said automatic exposure time control signal;   a switching member movable between a first position for effecting manual exposure control based on manually selected shutter speed and diaphragm aperture and a second position for effecting automatic exposure control for automatically controlling said diaphragm aperture and shutter speed; and   means for connecting said output signal to said exposure time control circuit and for disconnecting said automatic exposure time control signal to said exposure time control circuit with said switching member in said first position.   
     
     
       2. A multi-exposure control device as in claim 1 wherein said means for producing an automatic exposure time control signal includes a light measuring element and said signal is proportional to the logarithmic value of the light intensity impinging on said light measuring element, said output signal varies arithmetically relative to the geometrical shutter speed variation manually selected in said first mode, and said exposure time control circuit anti-logarithmically converts said automatic exposure time control signal. 
     
     
       3. A multi-exposure control device as in claim 1 further comprising means for interrupting the operation of said means for terminating exposure during operation of said diaphragm adjusting means and for enabling operation of said means for terminating exposure when said diaphragm adjusting means is inoperative. 
     
     
       4. A multi-exposure control device as in claim 1 further comprising means for arresting said switching member in said second position with said means for selecting in said second mode.